Syringes are now commonly used primarily to deliver various liquid medicaments via a syringe type device to a patient As used herein, “medicament” includes any powder or liquid medicament, drug or vaccine or combinations thereof which may be administered from a valved device into a patent, sometimes referred to herein as a valved delivery device. More recently, the prior art has proposed unit dose disposable powder medicament delivery devices, such as disclosed in U.S. Pat. No. 5,215,221, wherein a predetermined quantity or unit dose of a powder medicament is sealed in a reservoir formed between opposed thermoplastic sheets and expressed or delivered by application of manual force to a thermoformed blister which, upon activation, breaks a burstable seal between the sheets at the entrance to the reservoir and fluidizes the powder medicament in the reservoir through a delivery tube. The sealed delivery tube is cut prior to use.
There are several considerations affecting the design and efficacy of medicament delivery devices. First, it is important to ensure that a predetermined quantity or dose of medicament is consistently delivered to the user with each application. Second, because injection therapy often requires numerous applications, the cost of providing the dosage should also be considered. Thus, it is desirable that the medicament delivery device consistently expresses substantially the entire medicament to the user and that the delivery device is not susceptible to user error in operation. Third, it is important that the medicament be properly disbursed, dissolved, or entrained in the conveying fluid. Further considerations include the operating complexity, cost of the device, portability and size of the delivery device. It would also be desirable in certain applications to provide a reusable delivery device with a disposable standard medicament cartridge containing a unit dose of medicament which can be easily handled and replaced in the delivery device by the user without error. In other applications, a disposable delivery device is desirable.
Further, it would be desirable for an injection delivery device to deliver a controlled unit dose of a unitized medicament on demand. That is, it would be desirable to be able to charge or pressurize the medicament delivery device prior to use, such that the patient does not have to simultaneously manipulate the pressure delivery means, as by compressing a bulb or syringe, with the device inserted into the body, either via a needle or into a body orifice while delivering the medicament. This can be difficult for some patients to accomplish and may result in poor or partial delivery of the medicament.
The medicament delivery device of this invention provides a reproducible, high level of clearance of medicament or emitted dose from a replaceable cartridge, wherein a manually actuatable fluid pressure delivery device may be charged prior to use and then released on demand to deliver a controlled unit dose of a unitized medicament to the system of the patient.